This thesis studies the rescission action in insolvency proceedings from the point of view of procedural law, especially focusing on the procedural aspects of the action and the analysis of the judicial resolutions and the doctrine derived from it. Firstly, the substantive requirements legally established in order to use the action will be analyzed as well as the interpretation courts of law and academics have made on this point. Subsequently, the concept, legal nature, processing and effects of the action will be examined from a procedural perspective. Further, the main gaps, inconsistencies and problems regarding the regulation and processing that the practical application of the proceeding to annul the transactions has made possible to identify will be highlighted. Moreover, different solutions, often contradictory, have been offered by jurisprudence and subsequently been proposed as legal reforms. Finally, this thesis aims to defend the need to apply the regulations of this action straight from its origin and according to its main aim, thus avoiding the distortion caused by extensive interpretation. This work has been divided in four Titles. In the First Title, named "The rescission action in insolvency proceedings", the concept, the main goal, the previous and current regulatory framework and the legal nature of this action are examined. In the Second Title, named "Requirements for the use of the action", the substantive requirements needed in order to use the action, especially the temporal requirement and the objective requirement consisting of damaging the value of the insolvency estate will be studied. In the Third Title, named "Acts affected by the action", the acts and legal businesses which are rescindable and those who are not are analysed, taking special note of refinancing agreements. Lastly, in the Fourth Title, named "Procedural aspects of the rescission action in insolvency proceedings", the main procedural questions are studied, which are: jurisdiction and legal competence to deal with this action; the period for its exercise; legitimation; the availability of the action; the precautionary measures; the proceeding to annul the rescindible transactions; and the effects of the action and the problems they pose. Finally, the conclusions of this thesis are presented. This study was made taking into account a global perspective, keeping in mind the interests and rights of all the possible parties involved.